Pinking attachment for sewing machines



Jan. 26, 1937. N. PEDERSEN PINKING ATTACHMENT FOR SEWING MACHINES Fi led Aug. 17, 1935 3 Sheets-Sheet l jam. 2, 1%7. N. PEDERSEN PINKING ATTACHMENT FOR SEWING MACHINES File d Aug. 17. 1935 s Sheets-Sheet 2 3. 2%, 137. PEDERSEN PINKING ATTACHMENT FOR SEWING MACHINES Filed Aug. 17, 1935 5 Sheets-Sheet 5 Patented Jan. 26, 1937 UNITED STATES PATENT OFFICE Niels Pedersen, Drexel Park, Pa assignor of'onehalt to Sarah Spielman, Philadelphia, Pa.

Application August 1711935, Serial No. 36,721

22 Claim.

5 Nathan Levine No. 1,489,891, dated April 3, 1924, wherein the attachment is actuated by the needle bar of the sewing machine, by reason of which the attachment may be applied to any conventional type of sewing machine without necessitating any alteration or addition to any of the standard working parts thereof.

One object of the present invention is to provide theattachment with means for establishing a definite step-by-step movement of the pinking wheel in accordance with any given number of stitches per inch as produced by the stitching and feeding mechanism of the sewing machine.

Another object of the invention is to connect the adjusting mechanism of the attachment to the stitch regulating mechanism of the sewing machine in such a manner that the operator in adjusting the feeding mechanism of the machine to produce a given number of stitches per inch will automatically and simultaneously therewith adjust the actuating mechanism of the pinking wheel to produce a step-by-step movement of the pinking wheel in accordance with the feed of the machine.

Another object of the invention is to provide a universal mechanism for effecting any and all of the various step-by-step movements required of the pinking wheel to agree with the various rates of feed of the sewing machine; and to construct the actuating mechanism in such a manner that intermittent rotation of the pinking wheel will be accomplished by constantly engaged positively acting elements, as disinguished from the intermittently engageable pawl and ratchet or similar mechanisms commonly employed for providing intermittent rtation of a shaft.

Other improved features and the operation of the device as a whole will be fully disclosed hereinafter, reference being had to the accompanying drawings, of which:

Fig. l is a plan view of the attachment with a portion broken away for clarity;

Fig. 2 is a front elevation;

Fig. 8 is a. side elevation;

Fig. 4 is a sectional elevation taken on the line 4-4, Fig. 1;

Fig. 5 is a sectional elevation taken on the line 5-5, Fig. l;

Fig. 6 is a sectional elevation taken on the line 6-6, Fig. 1; and

Fig. '7 is a sectional elevation taken on the line 'l- -'l, Fig. 5.

This attachment primarily comprises a base 5 I which is adapted to rest on the work-supporting surface a of any conventional type of sewing machine A. Secured to the underside of the base I is a plate 2 which is arranged to replace the ordinary removable presser plate of 10 a sewing machine and to be secured to the bed plate a by the screws which are normally employed for securing the presser plate in place.

The plate 2 is provided with the usual parallel slots 3, 3, through which the feed dog teeth of the sewing machine feeding mechanism operate, and a hole 4 through which the needle of the sewing machine passes for cooperation with the shuttle or other stitch interlocking mechanism underlying the plate 2.

Adjacent the inner feed dog slot 3, with its axis disposed to the rear of the needle opening 4, is the pinking wheel 5. The pinking wheel 5 (see Fig. 4) is secured by screws 6, 6 to an enlarged head 1 formed on one end of a shaft 8. The pinking shaft 8 is rotatably mounted in bearings 9, 9a respectively mounted in and formed on a swinging frame l0 (see Figs. 1, 2 and 3).

The swing frame I0 is provided with bearings ll, Ha which are mounted for pivotal movement around a fixed shaft i2 mounted and secured by a screw l4, in a bearing [3 which is formed integral with the base I.

The pivot shaft I2 is provided with a reduced end I 5 on which is rotatably mounted an externally threaded sleeve IS. The threaded sleeve I6 is provided with a knurled flange or head I! and is held against longitudinal movement on the reduced portion [5 of the shaft l2 by and between the head of a screw l8, threaded into the outer end of the reduced portion i5 of the shaft I 2, and a shoulder l9 formed on the shaft i2 by the reduction of the portion I 5 thereof.

The threaded sleeve l6 has threaded engagement with internal threads formed in the beari ing ll of the swing frame l0, whereby rotation of the sleeve I6 will cause bodily movement of the frame in and consequently the pinking wheel 5 toward and away from the needle hole 4 in the plate 2, for widening or narrowing the width of the seam, i. e., for increasing or decreasing the width of that portion of the material lying between the line of stitches formed by the needle operating through the hole 4 and the outer points of the zig-zagged cut edge of the material as produced by the pinking wheel 5.

The pinking wheel 5 is adapted to be intermittently rotated at a peripheral speed equal to the linear speed of the cloth as fed by the feed dogs of the machine operating through the slots 3, the stroke of the dogs being regulated according to the number 01 stitches per inch required', the movement of the feed dogs being regulated by the stitch-regulating mechanism of the sewing machine itself, which can be set to 8, 10, 12, 14, 16, etc. stitches to the inch merely, for example, by loosening the stitch regulating knob B of the sewing machine A, as illustrated in Fig. 2 and by moving said knob upwardly or downwardly along the slot C as indicated by the double arrow in said figure until the desired number of stitches per inch is attained, whereupon by tightening the knob B, the machine is set for the definite rate of feed established. 4

In the present instance the intermittent rotation of the pinking wheel 5 is effected by an intermittent driving mechanism which includes a worm wheel 28 fixedly secured to the intermittently rotatable shaft 8 on which the pinking wheel 5 is mounted (see Figs. 4 and 5).

Mounted for pivotal movement about the shaft 8 is an oscillating frame 22. The rocking frame 22 is provided with an arm 23 to which is pivotally connected at l9 one .end of a link 24, the opposite end of which is pivotally connected at 2| to a block or sleeve 25 which is loosely and slidably mounted on a driving lever 26 (see Figs. 1 and 2). The driving lever 26 is pivotally mounted on a screw 21 carried by and fixed in a supporting block 28.

The pivot-supporting block 28 is slidably mounted for horizontal movement toward and away from the sleeve 25 in a guideway 29 which is formed on a bracket 30 carried by and preferably constituting an integral part of the swing frame ID. The slide 28 is provided, in the present instance, with a cam follower 3| in the form of the body of a screw which passes through a cam slot 32 formed in a cam lever 33, and is threaded into said slide, the head 34 of said screw being sufficiently spaced from said slide to permit relative movement between the cam lever and the slide without binding.

The cam lever 33 is pivotally mounted at 35 on the bracket 30 and is provided with an arm 36 which is connected by and through a link 31 and universal couplings 38 and 39 to the stitch regulating knob B of the sewing machine.

The driving lever 26 is of tubular construction at its outer end for receiving a pin 40 (see Fig. 1). The pin 40 has a head 4| which is pivotally mounted on a screw 42 threaded into an L-shaped bracket 43 (see Fig, 1). The bracket 43 includes a split arm 44 through which passes the needle bar D of the sewing machine, said bracket being clamped securely to the needle bar by a screw 45, so that vertical reciprocation of the needle bar effects oscillation of the driving lever 26, which in turn, through the block 25 and link 24, effects a resuItantoscillation of the lever 23 and the frame 22 of which the lever 23 is a part.

Meshing with the worm wheel 20 is a worm 46. The worm 46 has plain cylindrical ends 41 and 48 (see Fig. 5) which are rotatably mounted in bearings 49 and 56 forming part of or secured to the rocking frame 22.

Secured to the worm shaft 48 is a clutch wheel 5| (see Figs. 5 and '7) having a plurality of arms 52 each having a plain angular surface 53, between which and a plain circular inner peripheral surface 54 of a ring 55 is a spring pressed clutch ball or roller 56. The clutch ring 55 has a central web 51 at one side which is secured by screws 58 to the bearing 56 on the rocking frame 22, whereby the ring 55 is secured against movement relative to said frame. The rolls 56 are pressed into contact with and between the angular surface 53 of the arms 52 and the inner peripheral surface 54 of the ring 55 by springs 59, whereby the worm 46 and its shaft 48 are permitted rotation in the direction of the arrow at (Fig. 7) during rocking of the frame 22 in one direction and locking the shaft 48 and worm 46 rigidly to the rocking frame 22 during movement of the frame 22 in the opposite direction.

Likewise the intermittently rotatable shaft 8 is permitted free rotation in the direction of the arrow b (Fig. 6) during movement of the rocking frame 22 in one direction and is'locked against rotation during movement of the rocking frame 22 in the opposite direction. For this purpose the shaft 8 is provided with a drum or wheel 66, between the peripheral surface 6| of which and a fixed hardened plate 62, set at a slight angle to the vertical, a hardened roller 63 is normally pressed into a gripping or locking engagement with the peripheral surface 6| of the drum 68 and the hardened plate 62 by a spring 64. The plate 62 is mounted in a slot 65 formed in the swinging frame I0.

Freely rotatably mounted in a depression 66 formed in the presser plate 2 is a disc 61 (see Fig. 4) which functions as an anvil for the pinking wheel 5, said pinking wheel being pressed firmly into cloth-cutting contact with the anvil 61 by a spring 68 encircling a vertically projecting threaded stud 69 which is secured in and projects from the base plate I through an elongated slot 10 formed in the swing frame l8, said spring being interposed between the top surface of the swinging frame l and a nut 1| threaded on to the upper end of the stud 69, whereby the pressure of the pinking wheel on the anvil 61 may be regulated and maintained.

As the needle bar D descends, the arm 26 is rocked about its pivot 21, which, through the block or sleeve 25 and the link 24, rocks the frame 22 about the axis of the shaft 8. During this movement of the frame 22, the worm 46 is held against rotation and, due to the worm 46 being in positive intermeshing contact with the worm wheel 20 on the shaft 8, the shaft 8, and consequently the pinking wheel 5, are rotated in the direction of the arrow 0, Fig. 3. This occurs at the time the feed dogs of the machine are moving longitudinally through the slots 3, 3 in the direction of the arrow d, Fig. 1.

During the reverse movement of the needle bar D and the lever 26 the rollen 63 jams between the plate 62 and the peripheral surface 6| of the drum 66 on the shaft .8, which prevents backward rotation of the shaft 8, worm wheel 28 and pinking wheel 5. Thus with the worm wheel 20 held against rotation during this corresponding reverse rocking movement of the frame 22, the worm 46, the worm shaft 48 andthe clutch wheel 5| are caused to rotate in the direction of the arrow a, Fig. 7, the rollers 56 being moved against the action of the springs 59 to release the clutch wheel 5| from the stop ring 55.

As soon as the directions of movement of the needle bar D, lever 26 and frame 22 are again changed and these elements begin to move in the first said direction, the rollers 56 jam between the peripheral surface 54 of the stop ring and the inclined surface 53 of the arms 52 of the clutch wheel 5| and lock the worm 46 against rotation. Thus with the worm 46 locked in the frame 22 and positively intermeshing with the worm wheel 20 the worm wheel 20, and consequently the shaft 8 and drum 60, are caused to rotate in the direction of the arrows b and 0 (Figs. 3 and 6), the roller 63 by such movement of the drum 80 being released to permit of said movement.

Thus it will be seen, as the needle bar D reciprocates vertically, the pinking wheel 5 is given an intermittent rotation and thereby cuts the material being sewed simultaneously with the longitudinal feeding movement of the feed dogs of the sewing machine as said dogs advance the fabric away from the needle-penetrating or stitch point defined by the hole 4 in the plate 2 and the extent of each intermittent movement of the pinking wheel and feed dogsdetermines the length of the stitch, consequently the number of stitches per inch, which is normally referred to as the speed of feeding or rate of feed of the machine.

When it is desired to change the feeding speed to produce a greater or lesser number of stitches per inch, the stitch regulating knob B is loosened and moved upwardly or downwardly as the case may be, longitudinally of the slot C. This causes a rocking of the cam lever 33, through the link 31, and causes the cam surfaces of the cam slot 32 to move the slide 28 longitudinally in the guideway 29. Such movement of the slide 28 changes the relation between the pivot points 2| and .21 of the driving link Zfl and driving lever 26 respectively which alters 'the extent of oscillation of the rocking frame 22.

Such alteration afiects the extent of intermittent rotation cf the pinking wheel 5 and keeps such movements in accordance with the feeding speed of the feed dogs of the machine as determined by the position of the stitch regulating knob B along the slot C, it being understood that the knob B is mounted on a rod or lever which projects outwardly through the slot C and is connected inside the head E of the sewing machine to mechanism forming no part of the present invention which controls the extent of horizontal reciprocation of the feed dogs of the sewing machine for each vertical reciprocation of the needle bar D.

In order to change the width of the seam, i. e. to vary the distance from the line of stitches produced by the needle F to the extreme outer edge of the material as cut by the pinking wheel 5, the whole of the mechanism carried by the swing frame I0 is moved bodily in a direction axially of the shaft l2 by turning the threaded sleeve Hi. This movement however does not afiect the established synchronization between the feed the outer end of the driving lever 25 and the pivotal connection of said lever 26 with the driving link 24 is so slight that the above noted synchronization is in no wise materially affected, it being the change in the distance between the pivot 2| of the driving link 24 and the pivot 21 of the driving lever 25 which vitally affects the extent of intermittent rotations of the pinking wheel 5.

While the frame l0 has been referred to as a swing frame it will be understood that actually no swinging of the frame occurs unless something hard, such as a pin should accidentally pass between the pinking wheel 5 and the anvil 61 in which case the spring 68 would yield and permit the frame ID to swing upwardly to relieve the wheel 5.

The actual degree of contact between the peripheral cutting surface of the pinking wheel 5 and the plain surface of the anvil 6'! may be minutely regulated by turning a screw 15 (see Fig. l) which is threaded through the swing frame l0 and bears on and against the upper surface of the base I, so that only enough pressure is exerted by the pinking wheel to cut through the material lying on the anvil, whereby marring of the cutting edges of the pinking wheel by the hardened surface of the anvil is prevented.

The anvil 51 is mounted on ball bearings as illustrated in Fig. 4 which allows the anvil to turn freely in a substantially horizontal plane under. pressure and circular movement of the pinking wheel in a substantially vertical plane.

While the ratcheting mechanism above described is shown as being used in connection with a pinking attachment for sewing machines, it is adapted for general use in cases where it is desired to produce an intermittent rotation of a shaft but its application to .the pinking attachment is particularly valuable in that it will withstand the hard usage resulting from the high speed of a modern sewing machine capable of making between four and five thousand stitches per minute. Under such high speeds ordinary pawl and ratchet mechanism will not operate efiiciently over a long period, due to the pounding action of the pawl against the teeth of the ratchet wheel each time the pawl is oscillated in the direction to reengage and move the ratchet wheel. In the present case, with the worm constantly in engagement with the worm wheel the above noted destructive pounding action is entirely eliminated, consequently the device is capable of functioning efficiently over practically an unlimited period of time.

It is well known that intermittent steps of a shaft produced by conventional pawl and ratchet mechanism are limited to the extent of one tooth or to multiples of the spacing'from one to the next tooth. Therefore, such mechanism is not capable of movement giving any desired step-by-step rotation of the shaft, whereas the worm and worm wheel mechanism disclosed above is capable of producing any desired degree of intermittent rotation of the shaft, depending solely on the degree of oscillation of the worm carrier.

A roller clutch, while it may be capable of giving any desired step-by-step rotation of a shaft, will not stand up under heavy load and high speed for any great length of time due to the fact that the roller has but a line contact with the surfaces of thetwo relatively B of the stitch regulating mechanism has beenv movable surfaces of the clutch elements with which the roller makes contact.- Therefore, in a relatively short time the roller and/or gripping surfaces develop fiat spots which prevent the clutch from acting properly and accurately, whereas, in the worm and worm wheel ratcheting device there are three or four teeth of the worm wheel constantly engaged by a corresponding number of the convolutions of the worm which distributes the pressure over considerable areas of both elements, making the life of this form of device practically unlimited under all loads.

In order to secure the pivot 21 of the driv ing lever 26 in a fixed position, after the knob operated to provide a given number of stitches per inch and is tightened to secure such setting of the sewing machine, the slide 28 is provided with a lock stud 18 which is secured in the slide and projects rearwardly through a slot 19 formed in the guideway 29-. The outer projecting end of the stud 18 is provided with a nut 11 which when tightened clamps the slide to the guideway and prevents relative movement therebetween.

In order to take up or prevent lost motion between the rocking frame 22 and the worm 20 on the pinking wheel shaft 8, the frame 22 is provided with a lug through which is threaded in axial alignment with the worm shaft 48, a take-up screw 8l-which is provided with a lock nut 82 and acts as a thrust bearing for said worm shaft.

The worm 46 is a coasting worm and may,

be of either a single or multiple thread type with a suitably small pitch angle to enable the worm to carry a high percentage of the load regulating means and controlling said needle bar actuated means for varying the degree of intermittent rotation of the pinking wheel commensurable with changes in the stitch length as determined by said member.

2. An attachment for a sewing machine 1m ing variable stitch regulating means, said at-' 3. An attachment for a sewing machine having variable stitch regulating means, said attachment comprising a pinking wheel, means for intermittently rotating said wheel, including a pivoted driving lever and a motion transmitting element connected thereto in spaced relation to the pivot thereof, means for operatively connecting the driving lever to a normally invarying the degree of intermittent rotation of the pinking wheel.

4'. An attachment for a sewing machine having variable stitch regulating means, said attachment comprising a pinking wheel, means for intermittently rotating said pinking wheel including a pivoted driving lever arranged to be oscillated by a normally invariable operating element of the sewing machine,a motion transmitting element connected to said lever in spaced relation to the pivot thereof, and means arranged to be connected to and actuated by said stitch regulating means for varying the position of the lever pivot relative to said motion transmitting element for varying the degree of intermittent rotation of the pinking wheel.

5. An attachment for a sewing machine having variable stitch regulating means, said attachment comprising a pinking wheel, means for intermittently rotating said pinking wheel including a pivoted driving lever arranged to be oscillated by a normally invariable operating element of the sewing machine, a motion transmitting element connected to said lever in spaced relation to the pivot thereof, a variable mounting for the lever pivot, and means arranged to be connected to and actuated by said stitch regulating means for actuating said pivot mounting to vary the distance between the lever pivot and said motion transmitting element forvarying the degree of intermittent rotation of the pinking wheel.

6. An attachment for a sewing machine having variable stitch regulating means, said attachment comprising a pinking wheel, means for intermittently rotating saidpinking wheel including a pivoted driving lever arranged to be oscillated by a normally invariable operating element of the sewing machine, a motion transmitting element connected to said lever in spaced relation to the pivot thereof, a slide supporting the lever pivot, a guideway for the slide, and means arranged to be connected to and actuated by said stitch regulating means for actuating the slide to vary the distance between the lever pivot and the motion transmitting element for varying the degreeof intermittent rotation of the pinking wheel.

7. An attachment for a sewing machine having variable stitch regulating means, said attachment comprising a pinking wheel, means for intermittently rotating said pinking wheel including a pivoted driving lever arranged to be oscillated by a normally invariable operating element of the sewing machine, a motion transmitting element connected to said lever in spaced relation to the pivot thereof, a slide supporting the lever pivot, a guideway for said slide, a cam follower on the slide, and a cam engaging said follower and arranged to be connected to and actuated by said stitch regulating means for varying the distance between the lever pivot and the motion transmitting element to vary the degree of intermittent rotation of the pinking wheel.

8. An attachment for a sewing machine having variable stitch regulating means, said attachment comprising a pinking wheel, means for intermittently rotating said pinking wheel including a pivoted driving lever arranged to be oscillated by a normally invariable operating element of the sewing machine,a motion transmitting element connected to said lever in spaced relation to the pivot thereof, a slide supporting the lever pivot, a guideway for said slide, a cam follower on the slide, a cam lever having a cam surface engaging said cam follower, and a link connecting said cam lever with said stitch regulating means for actuation thereby to vary the degree of intermittent rotation of the pinking wheel.

9. An attachment for a sewing machine having variable stitch regulating means and a uniformly reciprocating needle bar, said attachment comprising a pinking wheel, means for intermittently rotating said pinking wheel, including a driving lever, means for connecting one end of the lever to said needle bar, means affording a support for the lever pivot at the opposite end of the lever, a motion transmitting element connected to the lever intermediate its said ends, and means arranged to be connected to and actuated by said stitch regulating means for varying the distance between the lever pivot and the point of connection of said motion transmitting element with said lever for varying the degree of intermittent rotation of the pinking wheel.

10. An attachment for a sewing machine having variable stitch regulating means, said attachment comprising a base arranged to be secured to the bed plate of the sewing machine, a. frame pivoted to said base, a pinking wheel rotatably mounted on said frame, means carried by said frame for intermittently rotating said pinking wheel including a driving lever, a pivot for said lever, a mounting for said pivot adjustably supported on said frame and means arranged to be connected to and actuated by said stitch regulating means for actuating said pivot mounting relative to said frame for varying the degree of intermittent rotation of the pinking wheel.

11. An attachment for a sewing machine comprising a pinking wheel, means for intermittently rotating said pinking wheel including a pair of relatively rotatable positively interconnected elements, means for supporting one of said elements for bodily oscillation about the axis of the second of said elements, means for operably connecting the second of said elements to said pinking wheel, and means for alternately locking said elements against rotation during the respective strokes of oscillation of the first element about the axis of the second element.

12. An attachment for a sewing machine comprising a pinking wheel, means for intermittently rotating said pinking wheel including a pair of relatively rotatable peripherally interlocking elements, means for supporting one of said elements for bodily oscillation about the axis of the second of said elements, means for operably connecting the second of said elements to said pinking wheel, and means for alternately locking said elements against rotation during the respective strokes of oscillation of the first element about the axis of the second element.

13. An attachment for sewing machines comprising a pinking wheel, a pair of intermeshing toothed elements, a carrier for one of said elements adapted for oscillation about the axis of the second of said elements, means for operatively connecting the pinking wheel to said a carrier for one of said elements adapted for oscillation about the axis of the second of said elements, means operatively connecting the pinking wheel to said second element, means for locking the first said element against rotation in said carrier during rocking thereof in one direction to effect concurrent rotation of the second of said elements and the pinking wheel, and means for locking the second said element against reverse rotation during reverse rocking of said carrier effecting rotation of the first said element by and about the second said element.

15. An attachment for sewing machines, comprising a pinking wheel, an intermeshing worm and worm wheel, means operatively connecting the pinking wheel and worm wheel, a carrier for the worm mounted for oscillation about the axis of the worm wheel, means for locking the worm against rotation in the carrier during rocking thereof in one direction to effect concurrent rotation of the worm wheel and the pinking wheel, and means for locking the worm wheel against counter-rotation upon reverse rocking of the carrier effecting rotation of the worm in the carrier by the inert worm wheel.

16. An attachment for a sewing machine, comprising a driven shaft, a pinking wheel secured to said shaft, a worm wheel secured to said shaft, a frame mounted for oscillation about the axis of the shaft, a shaft carried by the frame, a worm on said frame carried shaft and interlocking with the worm wheel on said driven shaft, and means for alternately locking said shafts against rotation during opposite oscillatory movements of said frame respectively for effecting intermittent rotation of said driven shaft and the pinking wheel.

17. An attachment for a sewing machine, comprising a driven shaft, a pinking wheel secured to said shaft, a worm wheel secured to said shaft, a frame mounted for oscillation about the axis of the shaft, a shaft carried by the frame, a worm on said frame carried shaft and interlocking with the worm wheel on said driven shaft, and a one-direction clutch means for each of said shafts arranged to lock said shafts alternately against rotation during opposite oscillatory movements of said frame respectively for effecting intermittent rotation of said shafts alternately.

18. An attachment for sewing machines, comprising a pinking wheel, a shaft to which said wheel is secured, a worm wheel secured to said shaft, a frame mounted for oscillation about the axis of said shaft, a worm rotatably mounted in said frame and meshing with said worm wheel, a driving lever, means for oscillating said driving lever, means operatively connecting said driving lever to said frame, and means for alternately locking said worm and worm wheel during the respective strokes of oscillatory movement of said frame.

19. An attachment for sewing machines, comprising a pinking wheel, a shaft to which said wheel is secured, a worm wheel secured to said shaft, a frame mounted for oscillation about the axis of said shaft, a'worm rotatably mounted in said frame and meshing with said worm wheel, a driving lever, means for oscillating said driving lever, means operatively connecting said driving lever to said frame, means for alternately locking said worm and worm wheel during the respective strokes of oscillatory movement of said frame and means for varying the distance between the pivot of said driving lever and the point of connection of said frame to said lever for varying the degree of oscillation of said frame.

20. An attachment for sewing machines, com-' for alternately locking said worm and wormwheel during the respective strokes of oscillatory movement of said frame, and means for shifting the pivot of the driving lever relative to the point of connection of the frame with said lever for varying the degree of oscillation of said frame.

21. An attachment for sewing machines having variable stitch regulating means, comprising a pinking wheel, a shaft to which said wheel is secured, a worm wheel secured to said shaft, a frame mounted for oscillation about the axis of said shaft, a worm rotably mounted in said frame and meshing with said worm wheel, a driving lever, means operatively connecting said driving lever to said frame, means arranged. to connect the driving lever with an operating element of the sewing machine to effect oscillation of said lever, meansfor alternately locking said worm and worm wheel during the respective strokes of oscillatory movement of said frame, and means arranged to be connected to said stitch regulating means for shifting the pivot of the driving lever relative to the point of connection of the frame with said lever for varying the degree of oscillation of said frame.

22. An attachment for a sewing machine hav- I ing a uniformly reciprocating needle bar and variable stitch regulating means including an adjusting member, said attachment comprising a pinking wheel, means actuated by said needle ,bar for intermittently rotating said wheel, and

means engageable with said adjusting member, 7 

